Dark spots on the photosphere are known as
a. solar wind.
b. the chromosphere.
c. the corona.
d. sunspots.

Photosphere is the surface of the sun that is visible to the eyes. It is believed to be one of the coolest part of the sun. The dark spots on the photosphere are known as the sunspots. Sunspots are usually visible in groups and are temporary because they only come and go. Magnetic fields are believed to have been involved in the occurence of the sunspots. Solar prominences are sometimes associated with the occurence of sunspots. They are active events that occur when sheets of gases are released from the active regions.

Ibelieve the answer is c. map projections.hope my answer has you : )